* Alternator Failure: The alternator charges the battery. If it fails completely, the battery quickly drains, leading to a complete loss of power. This is the most likely culprit given the symptoms.
* Battery Cable Issues: A corroded, loose, or broken battery cable (positive or negative) can interrupt the electrical flow, causing a sudden power loss. Check the cables for corrosion, tightness, and any visible damage.
* Main Power Wire Failure: A main power wire somewhere in the system could have come loose, broken, or corroded, interrupting power to the entire vehicle. This is harder to diagnose without tracing the wiring.
* Ignition Switch Problem: While less likely given the complete loss of power, a faulty ignition switch could be preventing power from reaching the rest of the system.
* Fuse Block Issue: A blown main fuse or a problem with the fuse block itself could cut power to everything. Inspecting the fuse block for blown fuses is crucial. Look carefully at the main fuses.
* Wiring Harness Damage: Rodents or other factors can chew through wiring harnesses, causing widespread electrical failure. This is more difficult to diagnose and often requires professional help.
* Battery Failure (Less Likely): While a completely dead battery would also cause this, it's less likely to happen suddenly while driving *unless* it had a pre-existing, significant internal fault. A failing battery typically shows warning signs before completely dying.
Troubleshooting Steps:
1. Check the Battery Cables: Inspect the positive and negative battery cables for corrosion, tightness, and breaks. Clean any corrosion with a wire brush and baking soda solution.
2. Check the Fuses: Thoroughly examine the fuse block for any blown fuses. Replace any that are blown, but be sure to use the correct amperage rating.
3. Try Jumping the Battery: If you can safely jump-start the truck, it strongly suggests an alternator or battery cable problem. If it runs briefly and dies again, the alternator is the prime suspect. If it doesn't start even with a jump, the problem may be elsewhere (battery, cables, or a larger electrical issue).
4. Visual Inspection: Look for any signs of damage to the wiring harness, especially around the battery and engine.
If you're not comfortable working with car electrical systems, have a qualified mechanic diagnose and repair the issue. Improper electrical work can be dangerous. The complete loss of power while driving indicates a serious problem that needs professional attention.
